The present invention relates to an improved water pipe connecting structure composed of a hexagonal locking nut, a coupling pipe, a connecting pipe, a metal fastening sleeve and a conic watertight washer. The connecting structure is adapted to watertightly connect with a water incoming pipe having an opening with arch reverse angle or having a plane open end.
FIG. 1 shows a conventional water pipe connecting structure which includes a hexagonal locking nut 10 formed with an arch inner flange 11 at one end, and an arch copper fitting 30 disposed in the locking nut 10. A lower arch surface 31 of the copper fitting 30 is snugly engaged with the arch inner flange 11, and a hard connecting pipe 20 is extended into the locking nut 10 and the copper fitting 30. Referring to FIG. 2, a water incoming pipe 40 having an open end with an inner reverse angle 41 is extended into the locking nut 10 with the reverse angle 41 engaged with an upper arch surface 32 of the copper fitting 30, whereby when the locking nut 10 is tightened to force the water incoming pipe 40 inward, the copper fitting 30 is binded with the hard connecting pipe 20.
Several shortcomings exist in such conventional connecting structure as follows:
1. The hard copper fitting can hardly reliably bind around the hard connecting pipe 20 and is apt to loosen and depart therefrom.
2. The engagement between the hard copper fitting and hard connecting pipe can hardly achieve a watertight effect and water leakage often takes place.
3. The conventional connecting structure is only suitable for a water incoming pipe having an open end with an inner reverse angle.
In order to solve the above problems, an improved connecting structure is developed as shown in FIG. 3, wherein the hexagonal locking nut 10 has an inner flange 12 at one end, and a coupling pipe 50 having an expansion neck portion 51 is fitted into the locking nut 10 with the neck portion 51 abutting against the inner flange 12 and a lower portion passing therethrough to insert into a metal fastening sleeve fitted with one end of a connecting pipe. The fastening sleeve receiving the lower portion is rolled and pressed so as to bind therewith. A plane watertight washer 52 is disposed around a head portion of the coupling pipe 50 above the neck portion 51 and a water incoming pipe 40 having a plane open end 42 is screwed into the locking nut 10 to watertightly engage with the washer 52 as shown in FIG. 4.
The above arrangement still has the following disadvantages:
1. The washer is apt to be deformed by the open end of the water incoming pipe, and after the locking nut is loosened, the washer tends to attach to the open end and then drop down. When re-loaded, the deformed washer can hardly snugly engage with the coupling pipe to achieve the watertight effect.
2. The plane watertight washer is only suitable for the water incoming pipe with a plane open end.
Therefore, it is necessary to provide an improved water pipe connecting structure which is able to firmly connect different water incoming pipes having different types of open ends while achieving a reliable watertight effect.